1. Field of the Invention
The present invention relates to an image forming apparatus (e.g., a laser printer or an electronic copying machine) for forming an image in accordance with image data supplied from a host apparatus.
2. Description of the Related Art
Conventionally, an image forming apparatus (such as a laser printer or an electronic copying machine) is connected to a host apparatus (such as a computer or an image reader), and forms an image on a sheet (i.e., an image forming medium) in accordance with image data supplied from the host apparatus. This type of image forming apparatus is expensive and yet it is not often accessed by the host apparatus. Therefore, effective use is not made of the image forming apparatus.
This problem may be solved by providing a multi-port type host interface for the image forming apparatus, so as to permit the image forming apparatus to be accessed by a plurality of host apparatuses. More specifically, the multi-port type interface incorporates a priority circuit that causes the image forming apparatus to be used in accordance with priority orders which are previously assigned to the ports of the interface circuit. If the image forming apparatus is simultaneously accessed by two or more host apparatuses, in other words, if it is simultaneously supplied with image data from two or more host apparatuses, the host apparatuses are selected in accordance with the priority orders and are thus connected to the image forming apparatus in accordance with the degree of emergency. By using the image forming apparatus on this time divisional basis, it is intended that efficient use may be made of the image forming apparatus.
However, in these conventional systems the priority orders assigned to the ports of the multi-port type interface are fixed. Therefore, if the operator wants to alter the priority orders, it is necessary to change the connection of cables. This operation is very troublesome and time consuming. Further, even if the operator wants the image forming apparatus to be temporarily accessed by a particular host apparatus, this cannot be done easily. That is, the operator must first turn off the image forming apparatus and then modify the cable connection, for temporary priority use of the particular host apparatus. Therefore, from a practical standpoint such temporary priority use is impossible.